| Subject | Re: [PATCH RFC 06/26] ipc: Replace spin_unlock_wait() with lock/unlock pair | From | Manfred Spraul <> | Date | Sat, 1 Jul 2017 21:23:03 +0200 |
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On 06/30/2017 02:01 AM, Paul E. McKenney wrote: > There is no agreed-upon definition of spin_unlock_wait()'s semantics, > and it appears that all callers could do just as well with a lock/unlock > pair. This commit therefore replaces the spin_unlock_wait() call in > exit_sem() with spin_lock() followed immediately by spin_unlock(). > This should be safe from a performance perspective because exit_sem() > is rarely invoked in production. > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Davidlohr Bueso <dave@stgolabs.net> > Cc: Manfred Spraul <manfred@colorfullife.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Alan Stern <stern@rowland.harvard.edu> > Cc: Andrea Parri <parri.andrea@gmail.com> > Cc: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Manfred Spraul <manfred@colorfullife.com> > --- > ipc/sem.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/ipc/sem.c b/ipc/sem.c > index 947dc2348271..e88d0749a929 100644 > --- a/ipc/sem.c > +++ b/ipc/sem.c > @@ -2096,7 +2096,8 @@ void exit_sem(struct task_struct *tsk) > * possibility where we exit while freeary() didn't > * finish unlocking sem_undo_list. > */ > - spin_unlock_wait(&ulp->lock); > + spin_lock(&ulp->lock); > + spin_unlock(&ulp->lock); > rcu_read_unlock(); > break; > }
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